## Algebra: A Combined Approach (4th Edition)

The denominator of a fraction or a rational expression must not equal 0 because when something is divided by 0, the result is undefined or it can't be found. When you divide 24 by 4, you're asking how many times can 4 go into 24: 24 = 4 + 4 + 4 + 4 + 4 + 4 4 goes into 24, 6 times. So 24 $\div$ 4 = 6 What about how many times can 0 go into 24: 24 = 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0... You can never reach 24, that's why anything divided by 0 is undefined.